diff --git a/netbox_agent/dell/dell.py b/netbox_agent/dell/dell.py
index 2835842..1e03e9f 100644
--- a/netbox_agent/dell/dell.py
+++ b/netbox_agent/dell/dell.py
@@ -27,5 +27,5 @@ class DellHost(ServerBase):
 
     def get_chassis_service_tag(self):
         if self.is_blade():
-            return self.dmi.get_by_type('chassis')[0]['Serial Number']
+            return self.dmi.get_by_type('Chassis')[0]['Serial Number']
         return self.get_service_tag()
diff --git a/requirements.txt b/requirements.txt
index 52dfc70..895d0a8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
 pynetbox==4.0.6
 netaddr==0.7.19
 netifaces==0.10.9
+pyyaml==5.1.2